Method of correcting data on a high-density recording medium

ABSTRACT

The present invention relates to a method of correcting data on a high-density recording medium such as a BD-ROM (Blu-ray ROM Disk) and a BD-RW (Blu-ray ReWritable Disk). In the present method, whether there is any error in a predetermined-sized LDC data block, which is included in a physical cluster, is determined based on if there is an error in sync data and BIS data neighboring the LDC data block, and, if determined to be erroneous, error correcting operation for the LDC block is conducted.

TECHNICAL FIELD

The present invention relates to a method of correcting errors in datarecorded on a high-density recording medium such as a BD-RW disk or aBD-ROM disk.

BACKGROUND ART

The standardization of new high-density read only and rewritable opticaldisks capable of recording large amounts of high-quality video and audiodata has been progressing rapidly and new optical disk related productsare expected to be commercially available on the market in the nearfuture. The Blu-ray Disc Rewritable (BD-RW) and Blu-ray Disk ROM(BD-ROM) are examples of these new optical disks.

As shown in FIG. 1, user data such as A/V data and various contents isencoded through multiple data processing steps to be recorded on theBD-RW. User data of a predetermined size is converted into data frames,scrambled data frames, a data block, a long distance code (LDC) block,and a long distance code (LDC) cluster in turn.

Similarly, user control data corresponding to the user data is convertedinto an access block, a burst indicating sub-code (BIS) block, and aburst indicating sub-code (BIS) cluster in turn.

As shown, a BIS cluster encoded in this manner is divided into 3 partsof the same size and each part is inserted between two data blocks of anLDC cluster, each data block being of a predefined size. Sync data isadded to one LDC cluster and one BIS cluster recorded in this manner,which constitutes one physical cluster.

As shown in FIG. 2, one physical cluster comprises 155 columns (syncdata exclusive) and 496 rows. In each 10 row, sync data has a size of 20bits, each of the first-column through fourth-column LDC data blocks hasa size of 38 bytes, and each of the first-column through third-columnBIS data blocks has a size of 1 byte. An Error in each 1-byte BIS datablock can be detected by conventional Reed Solomon (RS) decodingsequences.

If there are errors in the BIS data, for example, there are errors inboth of the BIS data adjacent to an LDC data block of size 38 bytes asshown in FIG. 2, it is concluded that the LDC data block contains anerror and the LDC data block is marked as erasure to indicate theexistence of the error.

Error correction can be done on the LDC data block marked as erasureduring RS decoding operation. Consequently, an error in the LDC datathat might be caused by scratches, fingerprints, etc can be correctedand user data can be normally reproduced.

The above-mentioned error correction method is only applicable to LDCdata blocks in the second or third column because a data error isdetected only when both BIS data blocks adjacent to an LDC data blockcontain errors. As shown in FIG. 2, an LDC data block (202) in the firstcolumn and an LDC data block (201) in the fourth column are adjacent tosync data and therefore error detection and error correction for thosedata blocks cannot be conducted.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide a method ofcorrecting errors in data recorded on a high-density recording mediumthat provides more accurate error correction by detecting an erroroccurring in an LDC data block based on errors in sync data and BIS dataadjacent to the LDC data block.

A method of correcting errors in data recorded on a high-densityrecording medium in accordance with the invention is characterized inthat it comprises the steps of: determining whether an error exists in along distance code block of a predefined size contained in a physicalcluster being reproduced from the high-density recording medium based onwhether errors exist in burst indicating sub-code data and sync dataadjacent to the long distance code block; and selectively performing anerror correction operation for the long distance code block depending onthe determination result.

The above-characterized present invention makes it possible to detectand correct errors in all LDC data blocks in a physical cluster thatmight be caused by scratches, fingerprints, etc.

BRIEF DESCRIPTION OF DRAWINGS

In the drawings:

FIG. 1 illustrates the process of encoding a physical cluster of theBlu-ray Disk Rewritable (BD-RW);

FIG. 2 illustrates the process of decoding a physical cluster of theBlu-ray Disk Rewritable (BD-RW);

FIG. 3 illustrates a schematic diagram of an optical disk reproducingapparatus in which the present invention may be advantageously embodied;

FIG. 4 illustrates the process of decoding a physical cluster of theBlu-ray Disk Rewritable (BD-RW) in accordance with the invention;

FIG. 5 illustrates a detailed block diagram for explaining the method ofcorrecting errors in accordance with the invention; and

FIG. 6 illustrates an exemplary embodiment of correcting errors inaccordance with the invention.

MODES FOR CARRYING OUT THE INVENTION

In order that the invention may be fully understood, preferredembodiments thereof will now be described with reference to theaccompanying drawings.

FIG. 3 illustrates a schematic diagram of an optical disk reproducingapparatus in which the present invention may be advantageously embodied.The apparatus comprises an optical pickup 11 for reproducing recordedsignals from an optical disk 10 such as a BD-RW disk or a BD-ROM disk, aVDP system 12 for converting the reproduced signal into a binary signal,retrieving digital data from the binary signal, decoding the digitaldata, correcting errors in data, and controlling the overall decodingoperation, and a D/A converter 13 for converting decoded digital datainto analog signals. The VDP system 12 responsive to a user requestperforms reproduction of the optical disk 10 loaded into the apparatus.

As shown in FIG. 4, it is determined whether an error occurs in an LDCdata block of size 38 bytes in the second or third column based onerrors in two BIS data blocks adjacent to the LDC data block. And, it isdetermined whether an error occurs in an LDC data block of size 38 bytesin the first or fourth column based on errors in a BIS data block andsync data adjacent to the LDC data block.

If an LDC data block is concluded to be erroneous, the LDC data block ismarked as erasure to indicate that an error occurs and an RS decoding isperformed on the LDC data block, thereby correcting the error that mightbe caused by scratches, fingerprints, etc.

As shown in FIG. 5, the VDP system 12 comprises a plurality ofconceptional blocks: a demodulation unit 120, a sync error detectingunit 121, a separating unit 122, a BIS deinterleaving unit 123, a BISblock buffer 124, a BIS decoding unit 125, an erasure checking unit 126,an LDC deinterleaving unit 127, an LDC block buffer 128, and an LDCdecoding unit 129. The sync error detecting unit 121 detects 20-bit syncdata from a data stream demodulated by the demodulation unit 120 andcompares the detected sync data with preset predictive sync data todetermine whether an error occurs in the sync data.

The separating unit 122 separates the data stream from the demodulationunit 120 into BIS data and LDC data. The BIS deinterleaving unit 123deinterleaves the BIS data and stores the BIS data in the BIS blockbuffer 124. The BIS decoding unit 125 performs RS decoding operations onthe BIS data stored in the BIS block buffer 124 to determine whether anerror occurs as shown in FIG. 4. The determination result is sent to theerasure checking unit 126.

Receiving determination results from the BIS decoding unit 125 and thesync error detecting unit 121, the erasure checking unit 126 determineswhether to mark an LDC data block as erasure. The LDC deinterleavingunit 127 deinterleaves LDC data from the separating unit 122 and storesthe LDC data in the LDC block buffer 128. The LDC decoding unit 128performs RS decoding operations on the LDC data stored in the LDC blockbuffer 128. If the LDC data block is marked as erasure by the erasurechecking unit 126, an error correction operation for the LDC data blockof size 38 bytes is conducted. Consequently, it is possible to correctan error occurring in an LDC data block in every column.

The sync error detecting unit 121 can divide 20-bit sync data into two10-bit half blocks and detect an error in each 10-bit half blockindividually. As shown in FIG. 6, an error in the first half can be usedto determine whether an error exists in a preceding LDC data adjacent tothe sync data, i.e., an LDC data in the fourth column. Likewise, anerror in the second half can be used to determine whether an errorexists in a following LDC data adjacent to the sync data, i.e., an LDCdata in the first column.

While the invention has been disclosed with respect to a limited numberof embodiments, those skilled in the art, having the benefit of thisdisclosure, will appreciate numerous modifications and variationstherefrom. It is intended that all such modifications and variationsfall within the spirit and scope of the invention.

1. A method of correcting errors in data recorded on a high-densityrecording medium, comprising the steps of: (a) determining whether anerror exists in a long distance code block of a predefined sizecontained in a physical cluster being reproduced from the high-densityrecording medium based on whether errors exist in burst indicatingsub-code data and sync data adjacent to the long distance code block;and (b) selectively performing an error correction operation for saidlong distance code block depending on the determination result.
 2. Themethod set forth in claim 1, wherein said step (a) concludes that anerror exists in said long distance code block if errors occur in bothsaid burst indicating sub-code data and said sync data and marks saidlong distance code block as erasure to indicate the error.
 3. The methodset forth in claim 1, wherein a portion of said sync data is used todetermine whether an error occurs in a preceding long distance codeblock adjacent to said sync data and the other portion of said sync datais used to determine whether an error occurs in a following longdistance code block adjacent to said sync data.
 4. The method set forthin claim 1, wherein said high-density recording medium is either aBlu-ray disk rewritable disk or a Blu-ray ROM disk.
 5. The method setforth in claim 1, further comprising the step of (c) determining whetheran error exists in said long distance code block based on whether anerror exists in preceding and/or following burst indicating sub-codedata adjacent to said long distance code block.